2. Check objects with Object Doctor, (see Tip#91).
3. Fix Intersecting, Self Intersecting, or Irregular Faces, (see Tip #96).
4. If you have Smooth objects convert them to facetted, (see Tip #93). Use the Polygon Mesh tool with all options turned OFF except the following: Polygon Type: All Triangles and Normal Angle Tolerance to 10°. Increase/decrease the Normal Angle Tolerance slightly to increase/decrease the amount of facetted triangles. Recheck the objects with the Object Doctor to see if this has introduced any issues. If desired keep a copy of your original Smooth geometry by saving to a new name or don't save the facetted version you create for the STL export. Note, you can export smooth objects directly to STL however the objects will be exported as facetted depending on the Display Resolution settings of the object, (see Tip #93).
5. Pre-mesh objects if necessary. Triangulating surfaces with a lot of holes or features can introduce irregularities, as the triangulation needs to make sure that each line inserted does not cross over other holes or features. If you apply a coarse Mesh to these faces first before triangulation then the number of holes per face is easily reduced and the triangulation can be applied more easily. Numerous mesh tools are available that can be applied at the object or face level. Note, don’t over mesh your geometry. Very dense meshes don’t always derive a better 3D print because the slicing algorithms used by the 3D printer can inherit anomalies in excessively dense areas.
Image A: Original Smooth object.
Image B: Smooth object pre-meshed with Mesh tools, (you can mesh the whole object or just selected faces).
Image C: Polygon Mesh tool to convert pre-meshed smooth object to facetted as described in step 4 above.
Image D: Polygon Mesh tool to convert original smooth object to facetted without a pre-mesh, (observe irregular triangulation around holes which is not recommended).
If needed you can use the UnMesh tool to remove meshing from your object, (see Tip #41).
6. Always Import your exported STL file back into formZ to examine and verify what you exported.